Yup, major difference! THe thing is, if you do the polishing right, you can damn near believe it's chrome. Look at ALMOST STOCK's GT40 intake. Half of it I would've sworn it was chromed if I didn't know any better.
Chrome powdercoat usually sucks. The trick with that is, the piece has to be perfectly flat to begin with otherwise it'll look like a real ****ty job. No offense to anyone who has any of it done, but you just can't compare it to real chrome like they would have you believe. Anyway, I had a bunch of spare AC brackets laying around, so I had them chrome powdercoated so I could sell them and get rid of 'em. And make a few bucks of course

Here's a pic at how they ended up:
Not bad for coating! Just realize before having anything done that it should be sanded as if you *are* polishing it. Or have the shop do it. Otherwise, like a polish or chrome job, it just won't refract the light right or end up very reflective (possibly miss out on a lot of the shine, too).
edit: Thanks guys

Coming from the guys who built my fave cars here on SN, it means a lot. I had nearly everything polished but I had to step it up to beat some people at some shows. Plus I was never fully happy with the intake. As the more-or-less centerpiece of the engine I felt it had to be absolutely flawless and no matter what I did I wasn't going to get it as good as chrome like the people I am referencing above. So, I had to one-up them...and I did so with a better chromer and better pre-polished base

After that I ended up with a fully chrome bracketed S-trim kit, so I replaced all my other stuff with that, basically for free after selling the old stuff. can't blame me for that eh?